Adjustable tensioning device

ABSTRACT

An adjustable tensioning device is described for applying a pulling force between two workpieces in which the pulling force may be adjusted while the pulling force is being exerted. The device is comprised of a central lever arm having a pair of workpiece engaging arms pivotably mounted on opposed sides of one end of the lever arm. One pivot axis of a work engaging arm is selectively movable through an adjusting mechanism along the lever arm to enable adjustment of the distance between the pivot axes of the two workpiece engaging arms. This feature enables changing of the mechanical advantage of the lever arm regardless of angular position thereof in relation to the work engaging arms and further enables such adjustment regardless of existing conditions.

United States Patent [1 1 James 1 1 Jan. 28, 1975 ADJUSTABLE TENSIONING DEVICE [76] Inventor: Glenn M. James, Rt. 1, Freshwater Bay Rd., Port Angeles, Wash. 98362 [22] Filed: Jan. 30, I974 1211 Appl. No.: 437,867

[52] U.S. Cl. 254/78 [51] Int. Cl 866i 3/00 [58] Field of Search 254/78, 77; 24/68 CT [56] References Cited UNITED STATES PATENTS 797,715 8/1905 Boyd 24/68 CT 1,666,592 4/1928 Brennan..... 254/78 X 2,247,642 7/1941 Neville 24/68 CT 2.824.717 2/1958 Yeager.... .1 254/78 3,425,098 2/1969 Bredvik 254/78 X Primary Examiner-Al Lawrence Smith Assistant Examiner-Robert C. Watson Almrney, Agent, or Firm-Wells, St. John & Roberts [57] ABSTRACT An adjustable tensioning device is described for applying a pulling force between two workpieces in which the pulling force may be adjusted while the pulling force is being exerted. The device is comprised of a central lever arm having a pair of workpiece engaging arms pivotably mounted on opposed sides of one end of the lever arm. One pivot axis of a work engaging arm is selectively movable through an adjusting mechanism along the lever arm to enable adjustment of the distance between the pivot axes of the two workpiece engaging arms. This feature enables changing of the mechanical advantage of the lever arm regardless of angular position thereof in relation to the work engaging arms and further enables such adjustment regardless of existing conditions.

2 Claims, 3 Drawing Figures ADJUSTABLE TENSIONING DEVICE BACKGROUND OF THE INVENTION The apparatus of the present invention relates to apparatus for applying a pulling force between two objects and more particularly to such apparatus utilizing a double fulcrum toggle mechanism and lever arm for enabling manual application of the pulling force.

Manually-operable tensioning apparatus are frequently used as chain binders for tightly binding or holding a load of loose material together. With conventional tighteners, it is often difficult to securely tighten the chain holding the load. The binder is usually connected to opposed ends of the chain in order to pull them together about the load. Often the distance between chain ends is insufficient to enable connection to the load binder or the chain is too loose and the binder is thereby unable to sufficiently tighten the chain about the load. These problems occur frequently when an op- ,erator attempts to connect one end of the binder to the chain wherein one link is spaced slightly too far away' from the binder hook and the next adjacent link is too close. If tension on the chain and the effort required to push down and lock the binder lever is too great, the lever may spring back with force sufficient to injure the operator. It may thereby be understood that previous load binders require that the chain links be located in ideal positions to enable the binder to operate efficiently and safely. Such conditions however are seldom experienced.

The above problems are realized to a limited degree in U.S. Pat. No. 3,675,897 granted to James A. Smith. Smith discloses a hand-operated tool for drawing together and clamping the ends of a length of chain. The tool includes a main arm and a second arm pivotably secured to the main arm. The pivot is located within a longitudinal slot in the main arm and includes means for adjusting the pivot longitudinally along the first arm. By utilizing a single pivot, the Smith apparatus is not capable of exerting significant pulling force between the chain ends. Further, the adjusting means for positioning the pivot along the first arm is adjustable only with the device in a substantially unloaded condition. A similar apparatus is disclosed in the Kenderdine U.S. Pat. No. 146,766.

U.S. Pat. No. 1,758,039 to I-laubert discloses a load binder that basically exemplifies the type of load binders commonly utilized to tighten chains or cables about a load of articles such as logs on a logging truck. The I-Iaubert device utilizes a lever with a double fulcrum toggle mechanism wherein the axis for the fulcrums is fixed on the lever handle. Although tremendous pulling force may be applied to connected ends of a chain, the basic problems described above remain unsolved.

It is therefore a principal object of my invention to provide a tensioning device that is much safer to operate and substantially easier to use than prior known devices of similar function.

It is another important object of my invention to provide a tensioning device that includes an adjustable fulcrum whereby variable tension adjustment may be made to the pulling force during or after locking of the lever handle.

A further object is to provide such a device that enables an operator to loosen or relax the pulling force prior to moving the lever handle from a locked position, thereby substantially decreasing the safety hazard over prior apparatus.

These and other objects and advantages will become apparent upon reading the following description. which, taken along with the accompanying drawings, disclose a preferred form of my invention.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred form of my invention is illustrated in the accompanying drawings in which;

FIG. 1 is a pictorial view of the tensioning device with sections thereof broken away;

FIG. 2 is an enlarged sectioned view taken substantially along line 22 in FIG. 1; and

FIG. 3 is a sectioned view taken along line 3-3 in FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT The device illustrated in the accompanying drawings was designed to enable manual application of a pulling force between two spaced workpieces. The term workpiece" is utilized herein to broadly define any object or objects that may be engaged on opposite sides of a lever arm 11 by first and second workpiece engaging means 12 and 13. One example of such an object is opposed ends of a chain utilized for binding a load of loose material such as logs or lumber to a truck bed. When utilized as such, the workpiece engaging means 12 and 13 would engage the opposed end links of the chain. I

Workpiece engaging means 12 and 13 are pivotably connected to the lever arm 11 at a bifurcated lower end 15 thereof. The first workpiece engaging means 12 is connected to lever arm 11 by a first set of fulcrum pins 16 extending through lever end 15 along a common fulcrum axis substantially perpendicular to the length of the lever arm. Workpiece engaging means 12 is comprised of a clevis 17 connected at one end to first fulcrum pins 16 and having a hook and link assembly 18 secured at the remaining end.

The second workpiece engaging means 13 is also pivotably mounted to lever arm 11 adjacent end 15 by a second fulcrum pin 20. Fulcrum pin 20 is carried by the lever arm about a fulcrum axis parallel to the axis of first fulcrum pin 16 and spaced therefrom longitudinally along the lever arm 11. Workpiece engaging means 13 includes a bar 21 pivotably connected to fulcrum pin 20 at an inside end and a hook and link as sembly 22 similar to assembly 18 connected to clevis 17.

Second fulcrum pin 20 is provided with an adjusting means 24 that enables the pin 20 to be longitudinally moved along lever arm 15 relative to first fulcrum pin 16. Adjusting means 24 is comprised of longitudinal slots 25, a connecting rod 26 and nut means 30. Slots 25 slidably carry the second fulcrum pin 20 for free longitudinal movement therein along lever arm 11. A clevis 27 is pivotably mounted to the second fulcrum pin 20 and is fixed to one end of connecting rod 26. Connecting rod 26 extends longitudinally within a longitudinal recess lever arm 11 to an outward handle end 28 of lever arm 11. Rod 26 includes a threaded end 29 that threadably communicates with nut means 30 at handle end 28. Nut means 30 frictionally engages the lever arm ll along an abutment surface 31. Surface 31 is illustrated in the drawing as an ordinary thrust washer.

To protect the threaded end 29, a protective shroud 32 is provided that completely encircles the nut means 30 and threaded end 29 of rod 26. Shroud 32 includes a plurality of apertures 33 that enable the lever arm 11 to be tied down in a locked position as a safety precaution.

Operation of the present invention is relatively simple and may be easily understood with reference to the above description and accompanying drawings. If, for example, my device is to be utilized to tighten a chain about a load or bundle of material, the hook link assemblies 18 and 22 are firstly engaged with the opposed chain ends. Adjusting means 24 may be utilized advantageously at this point to enable proper engagement of the hook link assemblies with the chain ends. This is done by rotating the nut means 30 on threaded end 29 of connecting rod 26. Such rotational movement of nut means 30 serves to move the second fulcrum pin longitudinally within slots and thereby adjust the total possible distance between hook link assemblies 18 and 22.

Once properly adjusted and with hook link assemblies 18, 22 engaging the opposed chain ends, the lever arm is then moved in a swinging motion toward first workpiece engaging means 12. This motion operates the fulcrum pins 16 and 20 against each other at sub stantially high mechanical advantage. The resulting movement of fulcrum pins 16 and 20 is designated in FIG. 3 by the directional arrows thereon. While moving in this direction, the work engaging means 12 and 13 initiate opposed pulling forces to the ends of the chain, tightening it about the load or bundle.

The lever arm 11 is designed to be swung to a position adjacent clevis 17 wherein the first and second fulcrum pins 16 and 20 are located in an over dead center position. In this condition, the opposition to the pulling force exerted by first workpiece engaging means 12 tends to force lever arm 11 further downwardly to a closed position against clevis 17. The opposition of the remaining chain end against the pulling force of second workpiece engaging means 13 also tends to force the lever arm 11 against clevis 17. Clevis 17 and the oppositional forces of the opposed chain ends prevents lever arm 11 from continuing in a swinging motion past the position wherein an abutment surface 35 on lever arm 11 and a complementary abutment surface 36 on clevis l7 abut one another. Abutment surfaces 35 and 36, in conjunction with the arrangement of fulcrum pins 16 and 20 on lever arm 11, may then be described as means for securing the device in a closed position while exerting opposed pulling forces against the workpiece.

The tension, or opposed pulling forces, applied to the workpiece is adjustable simply by rotating nut means on the threaded end of connecting rod 26. This is an extremely important feature of my invention since adjusting means 24 enables the tension to be adjusted while the lever arm is in the closed or locked position.

This feature is also particularly advantageous when an operator desires to move lever arm 11 back to an inoperative or relaxed position as illustrated in FIG. 1. Ordinarily, to move such a lever back to an inoperative position, the operator would forceably pull the handle end 28 of lever 11 away from abutment with clevis 17. Once the over center relationship is broken, a tremendous force is applied to the lever from the workpiece thereby forceably swinging the lever arm toward thesecond workpiece engaging means 13. However, with the present invention, the operator needs only to adjust nut means 30 to move fulcrum 10 longitudinally in slots 5 25 toward first fulcrum pin 16. This movement substantially relieves the pulling forces or tension applied to the workpiece and thereby facilitates safe movement of the lever arm 11 to an inoperative position. Once released as such, further adjustments are facilitated through the adjusting means 24 to further relieve workpiece tension by moving the fulcrum pins relatively apart.

It may have become obvious from the above description and accompanying drawings that various changes and modifications may be made therein. Therefore it is intended that only the following claims be taken as definitions of my invention.

What I claim is:

1. An adjustable tensioning device for operatively connecting and applying a pulling force between two spaced workpieces comprising:

an elongated lever arm;

first workpiece engaging means pivotably mounted by a first fulcrum pin to the lever arm along a first fulcrum axis adjacent one end of the lever arm for extending to one side thereof to engage a first workpiece;

second workpiece engaging means pivotably mounted by a second fulcrum pin to the lever arm along a second fulcrum axis adjacent the one end of the lever arm and spaced longitudinally thereon from the first fulcrum axis, for extending to an opposite side of the lever arm to engage a second workpiece;

the lever arm being manually operable to pivot relative to the first and second workpiece engaging means to move the fulcrum pins relative to each other in opposite directions to an over dead center position relative to each other and the lever arm to apply opposing pulling forces to the workpieces;

releasable securing means comprising an abutment surface on the lever arm engageable with a complementary surface on one of the workpiece engaging means when the fulcrum pins are moved to the over dead center position to limit further pivotal movement of the lever arm and thereby releasably secure the lever arms to the one workpiece engaging means; and

adjusting means operatively connecting one workpiece engaging means with the lever arm for manually adjusting the longitudinal distance between the fulcrum axes while the lever is operated to apply said opposed pulling forces to the workpieces.

2. The invention set out in claim 1 wherein the adjusting means is comprised of:

a longitudinal slot formed in the lever arm slidably receiving one of the fulcrum pins;

a rod connected to the fulcrum pin received in said slot and extending therefrom longitudinally along the lever arm terminating in a threaded rod end;

a rotatable nut means threadably engaging the threaded rod end; and

an abutment surface on the lever arm slidably engaging the nut means for preventing the nut means from moving longitudinally along the rod toward the fulcrum pin relative to the lever arm as the nut means is rotated; whereby selective rotation of the nut means on the rod serves to move the fulcrum pin correspondingly within the slot. 

1. An adjustable tensioning device for operatively connecting and applying a pulling force between two spaced workpieces comprising: an elongated lever arm; first workpiece engaging means pivotably mounted by a first fulcrum pin to the lever arm along a first fulcrum axis adjacent one end of the lever arm for extending to one side thereof to engage a first workpiece; second workpiece engaging means pivotably mounted by a second fulcrum pin to the lever arm along a second fulcrum axis adjacent the one end of the lever arm and spaced longitudinally thereon from the first fulcrum axis, for extending to an opposite side of the lever arm to engage a second workpiece; the lever arm being manually operable to pivot relative to the first and second workpiece engaging means to move the fulcrum pins relative to each other in opposite directions to an over dead center position relative to each other and the lever arm to apply opposing pulling forces to the workpieces; releasable securing means comprising an abutment surface on the lever arm engageable with a complementary surface on one of the workpiece engaging means when the fulcrum pins are moved to the over dead center position to limit further pivotal movement of the lever arm and thereby releasably secure the lever arms to the one workpiece engaging means; and adjusting means operatively connecting one workpiece engaging means with the lever arm for manually adjusting the longitudinal distance between the fulcrum axes while the lever is operated to apply said opposed pulling forces to the workpieces.
 2. The invention set out in claim 1 wherein the adjusting means is comprised of: a longitudinal slot formed in the lever arm slidably receiving one of the fulcrum pins; a rod connected to the fulcrum pin received in said slot and extending therefrom longitudinally along the lever arm terminating in a threaded rod end; a rotatable nut means threadably engaging the threaded rod end; and an abutment surface on the lever arm slidably engaging the nut means for preventing the nut means from moving longitudinally along the rod toward the fulcrum pin relative to the lever arm as the nut means is rotated; whereby selective rotation of the nut means on the rod serves to move the fulcrum pin correspondingly within the slot. 